On the Use of Darcy Permeability in Sheared Fabrics

Abstract

Determination of a set of processing parameters for a given material type is a complex process, and much work has been done using the framework developed in the last century by Darcy. While this model, assuming Newtonian flow through a granular (essentially a smoothed, porous) medium, has produced useful flow front progression simulation tools, a commonly arising problem in the fabrication of complex components is the modeling of flow front through regions of locally high shear. Several current approaches stem from a modification of the Darcy description using "local" permeabilities for these regions, differing from the permeabilities experimentally obtained in the unsheared or undeformed state. The work presented here investigates the applicability of a transformation of the permeability in the unsheared state, and conjectures that the driving forces for the fluid flow may be sufficiently complex to merit more detailed constitutive modeling in complex fabric architectures. Experiments on sheared fabrics have been performed, and permeabilities are compared with those obtained by tensor-transformation of unsheared fabric permeabilities.